A study of the mechanism by which polycyclic hydrocarbons induce breast carcinogenesis in the rat is proposed. The metabolism of 7,12-dimethylbenz (a) anthracene (DMBA) will be undertaken in breast tissue and the possible intermediate formation of the K-region epoxide of DMBA will be investigated. The synthesis of a new series of hydrocarbon diols will be carried out and their carcinogenicity, estrogenicity and possible formation in biological systems will be studied.